Concomitant CMV colitis in patients with moderate to severe ulcerative colitis admitted to a tertiary hospital in Iran: a retrospective study of frequency, risk factors, and subsequent clinical outcome

Cytomegalovirus (CMV) infection is a complication in patients with moderate to severe ulcerative colitis (UC), particularly during disease flares. This retrospective study aims to assess the frequency of CMV colitis, identify associated risk factors, and evaluate its impact on the clinical outcomes of UC patients in Iran. We conducted a retrospective study on 164 UC patients admitted between 2017 and 2023 at Imam Khomeini Hospital, Tehran, Iran. Admission for UC flare and colonoscopy with biopsy for CMV detection, via immunohistochemistry (IHC) served as inclusion criteria for enrolling patients in the study. Data on demographics, disease activity, and laboratory values were collected. Statistical analyses were performed to assess risk factors for CMV colitis and its impact on clinical outcomes including hospital length of stay, anti-TNF therapy, and colectomy rates. CMV colitis was diagnosed in 16.5% (27/164) of UC patients. In our logistic regression analysis, independent risk factors for CMV colitis in UC patients included a history of prednisolone use (OR = 3.45, 95% CI: 1.21–9.88, p = 0.021), concomitant PSC (OR = 7.11, 95% CI: 1.90-26.68, p = 0.004), higher Mayo Disease Activity Index (OR per score = 1.80, 95% CI: 1.17–2.79, p = 0.008), and elevated ESR (OR per unit = 1.02, 95% CI: 1.00-1.04, p = 0.019). CMV-positive patients were more likely to require anti-TNF therapy (OR = 2.49, 95% CI: 1.01–6.12, p = 0.047), experienced longer hospital stays (β = 2.62, 95% CI: 0.87–4.36, p = 0.004), and had a higher risk of colectomy during follow-up (OR = 3.13, 95% CI: 1.06–9.29, p = 0.040). In this cohort of Iranian UC patients, CMV colitis was prevalent in 16.5% of cases and independently associated with prior prednisolone use, concomitant PSC, higher Mayo DAI, and elevated ESR. CMV-positive patients had significantly increased odds of requiring anti-TNF therapy, prolonged hospitalization, and colectomy. Early diagnosis and targeted management of CMV colitis are critical to mitigating adverse outcomes in moderate-severe UC.